What material did you get these cut from? SendCutSend doesn't seem to have a very broad range of materials.
I shot myself in the foot with my layouts. I had the hub face further away from the spindle than it was in reality. So my 1/2" or 3/8" adapter plate on the front of the spindle turned into less than a 1/4" plate once I cut down another rotor and put it on a spindle so I could get some actual measurements. So now the adapter has to go on the backside of the spindle and I need more than an 1" of spacers to get the caliper in the correct location.
The other option is a GT500 rotor with the SP caliper. That one would use better than an 11/16" plate thickness, but SendCutSend seems to top out at 1/2" for the milder stuff and only 1/4" for 4130. And the smaller GT500 rotor seems to make getting it to all fit a little tougher.
I guess if it was easy, everyone would do it.